[FFmpeg-user] Best way to scale interlaced video

[Nicholas Robbins]

> On Tuesday, February 25, 2014 3:11 PM, Andrey Aleksandrovich <andrey.aleksandrovich at googlemail.com> wrote:

> > On 2/25/14, Massimo Battistel <battistel at gmail.com> wrote:
>>  hello,
>>  I have to scale 16:9 interlaced 1080i video down to PAL 576i 4:3 with black
>>  bars.
> 
> Do you really need 4:3 aspect?
> 
> If so, you can do something like that chain:
> 1920x1080 at 50i -> (lossless codec) 1920x540 at 50p -> (lossless codec)
> 720x576 at 50p -> 720x576 at 50i

I think this is actually a terrible idea. Rescaling the interlaced fields will introduce artifacts. I see that the scale filter has an "interlaced aware scaling" option that seems to be what he should use. With that in mind, I think his question of "how does interlaced aware scaling work" is the real questions.

> It is the best way to save time resolution (frame fields - fine motion
> scenes), while the static scenes will be little worse, cause of
> upscale fields from 540 to 576. However, you can to do not upscale and
> replace those 36 lines with black borders. Aspect ratio will be lost
> corrupt.